Thousands of Serb nationalists gathered Sunday in Bosnia and in Belgrade to protest the arrest of fugitive Bosnian Serb general Ratko Mladic, whom many consider a wartime hero.

Supporters of the ultra-nationalist Serbian radical party and other far-right organizations were bused in from across the region for demonstrations set to begin Sunday evening in the Serbian capital. Earlier, in the Bosnian town of Kalinovik, at least 1,000 people - many of them former Bosnian Serb soldiers - waved posters of hometown hero Mladic and accused Serbian President Boris Tadic of treason.

Mladic faces genocide charges from the 1995 massacre of up to 8,000 Muslim men and boys at Srebrenica. He was arrested Thursday northeast of Belgrade after 16 years on the run.

On Sunday, Mladic's son told reporters his father had nothing to do with the Srebrenica massacre - the worst atrocity in Europe since World War II. Darko Mladic - at odds with the findings in multiple probes of the massacre - said his father had in fact "saved so many women, children and fighters." Anything else, he said, occurred without his father's knowledge.

Serbian authorities said they would allow the Belgrade protests to take place, but they said security is high and warned that police will intervene as necessary.

Mladic also faces charges related to the three-year siege of the Bosnian capital, Sarajevo, during the 1992-1995 Bosnian war.

The U.N. tribunal on war crimes in the former Yugoslavia indicted Mladic in 1995 for war crimes and crimes against humanity during the Balkan wars of the 1990s.